a program?

Anyone know of a program that can keep track of weekly bandwith use? i'm going to need one because the school i'm going to next semester limits weekly bandwith use and they don't warn you or anythign when you go over they just penalize you.
i was really hoping there'd be a program that could monitor bandwith then maybe give me a weekly total used. my school is going to limit bandwith to 1.5 GB per week i think which really sucks for me because i download a lot of thinks.
there are programs like that try to search google for like bandwidth monitor or something similar sorry i cant remember any exact programs but there are a few for sure that do the exact thing you want